Sociotechnical systems like railways are becoming increasingly complex as numerous changes are constantly being integrated to improve or maintain desired performances. A crucial aspect enabling this integration is to define the scope of the changes, referred to as the system of interest. This can be challenging for engineering managers due to mounting system complexity caused by: an inter-organizational environment, a multitude of diverse stakeholders, the multidomain environment, and an increasing number of interdependencies. By employing Design Science Research, this study proposes an analysis that supports engineering managers in managing sociotechnical and inter-organizational change integration (MOSAIC) by facilitating a structured, multidisciplinary assessment of system impacts and interdependencies. The design was evaluated by applying it to an inter-organizational project in the Dutch railway system. The findings show that with MOSAIC, a system of interest can be collectively defined using the proposed process and a multidisciplinary and inter-organizational group of experts, creating mutual understanding. MOSAIC can further aid engineering managers in front-end project planning.